Psychophysical and electrophysiological techniques will be used to examine temporal factors and color vision in humans and primates. Color naming will be employed on a large subject population, to obtain evidence concerning individual differences in normal color vision, and to explore the relation of these to color blindness. Three psychophysical techniques will be used on a smaller number of subjects with the aim of refining color theory. These are: (1) methods of opponent-color cancellation; (2) measures of chromatic border contrast; and (3) studies of chromatic adaptation. Intraretinal recording, utilizing the late receptor potential, will be used to examine spatial parameters of chromatic vision in primates. As a precursor to the work on spatial vision, an attempt will be made to measure distributions of retinal illuminance in the intact eyes of living monkeys. Temporal factors will also be examined, using both psychophysical and electrophysiological response indicators.